It may be you got some bad plugs. I have had that happen from time to time, even with OS plugs. I don't know if its shipping or nicks in the filiments or what, but evey once in a while a plug doesn't last as long as it should, or doesn't tune as others of the same brand and type do. I haven't seen a correlation of this happening in one brand or another, it has happened that I can recall to OS, Fox, and K&B. Not yet to Enya plugs, but because of expense I don't use those as often.